1. Field of the Invention
The present invention relates to workholding apparatuses and, more particularly, is directed to a modular collection of apparatuses adapted to interchangeably support at least one vise-like clamping assembly therein to create a variety of different workholding apparatuses.
2. Description of the Invention Background
Today, most modern machine shops are typically equipped with one or more computer numerically controlled ("CNC") machining apparatuses which can perform very precise machining operations on "workpiece(s)" at very high speeds. However, because such CNC machining devices typically cost several thousands of dollars and require a substantial economic investment to support their operation, it is desirable to keep that equipment operating as close to one hundred percent of the time as possible. The time that a CNC machining device remains idle while workpieces are being handled or manipulated to other machining orientations represents a loss in efficiency of use of the machine and, ultimately, a loss in the profitability of the workpieces or an increase in their cost.
A single CNC machine can generally perform a variety of different "machining" operations on a workpiece. For example, a CNC milling machine can be utilized for many machining operations including producing flat ends on workpieces, producing planar surfaces on workpieces, and drilling, tapping, and reaming holes in workpieces. A typical CNC milling machine is equipped with a vertically or horizontally mounted spindle that has a tool holder attached thereto. The tool holder is constructed to operably receive and support a tool therein which may comprise an end mill for producing flat ends, a flycutter for producing planar surfaces, a drill for drilling holes, a tap for producing threaded holes or a reamer for sizing holes to very precise dimensions.
Such milling machines are equipped with a milling table that is adapted to support workpieces or workpiece-supporting apparatuses commonly known as "workholders" thereon. A milling table is typically coupled to the milling machine by means including computer-controlled positioning devices. The table and/or spindle can be moved relative to one another very precisely along "X", "Y", and "Z" axes. Such relative movement defines a cubical area known as the "machining envelope" in which the milling machine is capable of performing various machining operations therein. As such, to maximize the machine's production, it is desirable to support as many workpieces as practical in machining orientations within the machine's machining envelope to reduce the amount of machine "downtime" encountered when replacing or reorienting workpieces within the machining envelope.
To achieve very accurate workpiece dimensions, the workpiece(s) must be supported within the machining envelope in very precise location(s) that are recognized by the computer. The workpiece(s) may be supported within the machining envelope by tool fixtures or clamps that are attached to the milling table or they may be supported in vise-like workholders such as the ones disclosed in U.S. Pat. No. 4,928,937 to Bernstein, U.S. Pat. No. 4,898,371 to Mills et al., U.S. Pat. No. 4,569,509 to Good, and U.S. Pat. No. 4,098,500 to Lenz. As can be gleaned from review of those patents, such vise-like workholders are adapted to clamp a single workpiece between opposing jaw members operably supported on a base that is adapted to be clamped or attached by other known locating and attachment methods to the milling table.
Depending upon the size(s) of the workpiece(s) to be machined, a plurality of such "single-station" vise-like workholders can be attached to the milling table or to a "grid plate" adapted to be attached to the milling table. Such workholders, however, due to their limited ability to secure numerous workpieces within the machining envelope, do not serve to maximize the use of a machine's machining envelope and, thus, fail to reduce the amount of machine downtime encountered when changing or reorienting workpieces. Moreover, such workholders typically only serve to present workpieces in a single machining orientation to the machine's spindle.
For most multiple-workpiece machining operations, vise-like workholders, that are each capable of holding two or more workpieces in side-by-side orientations, are more desirable than the workholders described above. Examples of such "two-station" workholders are disclosed in U.S. Pat. No. 5,098,073 to Lenz, U.S. Pat. No. 5,094,436 to Stephan, III, U.S. Pat. No. 5,022,636 to Swann, U.S. Pat. No. 4,934,674 to Bernstein, and U.S. Pat. No. 4,529,183 to Krason et al. Such workholders typically comprise a base that has a central jaw fixed thereto. Two outer jaws are operably supported on the base and can be selectively positioned relative to the fixed central jaw by a vise screw that is operably received in a longitudinal slot provided in the base. Again, however, those workholders do not make full use of the machine's machining envelope and, in most cases, can only present the workpieces in a single machining orientation.
In an attempt to maximize the use of the machining envelope using the above-mentioned workholding devices, a plurality of such devices are typically attached to the milling table in a side-by-side arrangement for presenting multiple workpieces to the spindle of the machining device. However, such side-by-side arrangements typically fail to maximize the use of the machining envelope in the "Z" direction even though many workholding devices may be used. Such inefficient use of the machining envelope requires the use of many relatively expensive workholding devices which, in some cases, require substantial storage space when not in use.
In an effort to address this problem, a number of modular workholding systems have been developed that, in general, comprise differently shaped support members that can support a variety of workpiece clamping members thereon that are relatively easy to store. For example, U.S. Pat. No. 4,125,251 to Jamieson, Jr. discloses a universal clamping system that comprises a collection of differently shaped clamping members that can be selectively interconnected in clamping configurations by threaded rods. Another workpiece clamping system is disclosed in U.S. Pat. No. 4,711,437 to Longenecker et al. In general, that patent discloses a column formed from interconnected grid plates each having a plurality of holes and bores in an X-Y pattern therein. Workpiece clamping members are adapted to be accurately attached to the grid plates in a variety of different workpiece supporting orientations. Yet another modular workpiece supporting system is disclosed in U.S. Pat. No. 4,968,012 to Haddad et al. Such system generally comprises a collection of removable clamping members that can be removably attached to an apertured base member by locating bushings and screws.
All of the above-mentioned systems, while providing a substantial amount of flexibility for securing a variety of differently shaped workpieces in various workholding orientations, they comprise clamping members that can be easily lost and/or damaged. Furthermore, they are incapable of selectively indexing workpieces within a machining envelope. Thus, those workholding systems cannot automatically reorient workpieces within a machining envelope to enable a plurality of different workpiece surfaces to be machined without substantially interrupting the machining process to permit the workpieces to be manually reoriented. A number of indexable workholding devices are known. However, such devices typically lack the flexibility of the modular workholding apparatuses and systems discussed above.
Thus, there is a need for a modular workholding system that includes components that can be easily stored and not easily lost or damaged. There is a further need for modular vise-like workholding components that can be attached to a support member in a variety of different workholding orientations. There is still another need for a modular workholding system that has components that can be configured to selectively indexably support at least one vise-like workholding component about an axis such that multiple surfaces of multiple workpieces can be machined without substantially interrupting the machining process to reorient the workpieces.